This invention relates generally to apparatus for forming wooden frames and the like, and more particularly, to providing discrete connector plates from a coil of connector plate stock.
Connector plates having integrally formed nail-like teeth depending from a surface are used to fabricate various wooden frames, crates, trusses, and the like. Connector plates are used because of the ease and speed of fabrication which translates to lower costs. Typically, wooden members are placed on a jig table, and positioned in the form of the desired frame. Then, connector plates are positioned on opposite sides of the frame joints. The teeth of the connector plates are then embedded into the wooden members, usually, with a press.
To improve efficiency, at least some known presses include feed systems that index a desired length of connector plate coil stock into the press machine. The machine cuts a connector plate from the coil, positions the plate over the frame joint, and then presses the connector plate to embed the teeth of the connector plate into the wooden members. An example of such a press is described in U.S. Pat. No. 3,913,816.
The press described in Pat. No. 3,913,816 includes a coil feed assembly that advances two coils into the press. The coils are typically fabricated from an elongate strip of sheet metal connector plate coil stock having a plurality of spaced open slots formed by pre-punched, integrally formed elongate nail-like teeth extending from one surface of the connector plate stock. The first coil supplies connector plates for the top side of the frame joint and the second coil supplies connector plates for the bottom side of the frame joint. The connector plate coil stock is advanced into the press by a slide block coupled to an air cylinder. Additional air cylinders move clamps into engagement with the coils of connector plate coil stock to hold the coil stock to the slide block as the slide block advances the coil stock into the press. The clamps are released by retracting the air cylinders and then the slide block is moved back to its original position by retracting the air cylinder. The process is then repeated for the next pair of connector plates. This press relies on the action of air cylinders to move the coil stock into the press. As air cylinders wear they become less reliable and sometimes stick in one position. A buildup of dirt on the cylinder rod may prevent the rod from moving smoothly through the cylinder seals and may cause the cylinder rod to stick or move slowly. The 3,913,816 press includes air cylinders for advancing the first coil, and air cylinders for advancing the second coil. If any one cylinder moves slower than the others or sticks, the press could malfunction and jam.
It would be desirable to provide a connector plate coil advance drive that is reliable to smoothly advance connector plate coil stock into a press without the use of hydraulic or air cylinders.